An excellent program: as I use Macs it enables me to get good use out of the reader. A couple of thoughts:

Is there any possibility of Calibre being able to create groups?

Italics: in many text e-books underscore is used to indicate italics, thus:
_italic section_

When I was using Palm Reader I was able to use find-and-change in a word processor to change space-_ and _-space to \i to toggle italics (worked fine unless I missed one, in which case the rest of the book was in italics...). Is this sort of thing possible in .lrf? and if so could Calibre include an option to convert to the italics tag?